Security notes

As you can see in User Permission note, Grafana doesn't restrict any queries to the database. So you should be careful
and create a special user with limited access to Zabbix database. Grafana-Zabbix plugin uses only SELECT queries to
history, history_uint, trends and trends_uint tables. So it's reasonable to grant only SELECT privileges to
these tables for grafana user. But if you want to use this MySQL data source for querying another data, you can
grant SELECT privileges to entire zabbix database.

Also, all queries are invoked by grafana-server, so you can restrict connection to only grafana host.

GRANT SELECT ON zabbix.* TO 'grafana'@'grafana-host' identified by 'password';